In the human pharmaceutical arts, the rapidly developing resistance of known bacterial strains to currently prescribed pharmaceuticals has initiated a vigorous search for new classes of antibacterial agents having alternative modes of action. For example, methicillin resistant S. aureus (MRSA), vancomycin resistant Enterococcus (VRE) and penicillin resistant S. pneumo (PRSP) are bacterial strains which do not respond well to current clinical drug therapies.
Peptidoglycan is an essential cell wall polymer which forms a sacculus around the bacterial cell. The biosynthesis of peptidoglycan provides a unique and selective target for antibacterial activity. Peptidoglycan biosynthesis requires ten specific enzymes to perform as many synthetic transformations. These enzymes include MurA, MurB, MurC, MurD, MurE, MurF, MurG, MraY and the transglycosylase and transpeptidase families of enzymes. Inhibition of any one of these essential enzymes leads to loss of cell shape and integrity followed by bacterial death. This applies to both Gram positive and Gram negative microorganisms (Bugg, T. D. et al., Natural Products Reports 1992 199-215). Of these ten essential enzymes, β-lactam antibiotics inhibit transpeptidases, vancomycin inhibits transglycosylases and fosfomycin inhibits MurA.
In the animal health arts, virtually all commercial and most companion animals are affected by ecto- and endoparasites. The outcome associated with said parasitic infection or infestation in said animals is generally clinical disease and subclinical conditions that decrease performance. Insects, such as Phthiraptera (lice) and Diptera (flies), are among the most economically important ectoparasites in animal production. Insects, such as Siphonáptera (fleas), are highly pesteriferous to companion animals. Helminths, such as Trichostrongylus colubriformis, Haemonchus contortus, or the like, are among the most economically important endoparasites in animal production. Nematodes are highly pesteriferous to companion animals. Ecto- and endoparasitic infections and infestations not only seriously effect the economies of raising livestock for meat, wool, hides and milk, but are also a source of great concern for companion animals. New, economic alternative methods and compositions for the prevention, treatment and control of ecto- or endoparasites in warm-blooded animals are constantly being sought.
Therefore, it is an object of this invention to provide compounds which inhibit the Mur family of enzymes and are useful as antibacterial agents, particularly against resistant strains of bacteria.
It is another object of this invention to provide therapeutic methods and pharmaceutical compositions for the treatment of bacterial infection or disease.
It is also an object of this invention to provide an effective method for the prevention, treatment or control of ecto- or endoparasitic infection or infestation in homeothermic animals.
It is a further object of this invention to provide an ecto- or endoparasiticidal composition suitable for use on animals and humans.
It is a feature of this invention that the compounds provided herein act as effective inhibitors of bacterial cell wall biosynthesis via the Mur enzyme pathway.
Other objects and features of the invention will become more apparent by the detailed description set forth hereinbelow.